Reclaimed Asphalt Pavement in Asphalt Mixtures: State of The Practice

FOREWORD

Recycling asphalt pavement creates a cycle of reusing materials that optimizes the use of natural resources. Reclaimed asphalt pavement (RAP) is a useful alternative to virgin materials because it reduces the need to use virgin aggregate, which is a scarce commodity in some areas of the United States. It also reduces the amount of costly new asphalt binder required in the production of asphalt paving mixtures. This report informs practitioners about the state of the practice for RAP use in the United States as well as best practices for increasing the use of RAP in asphalt pavement mixtures while maintaining high-quality pavement infrastructures. High percentage RAP mixtures are achieved with processing and production practices, resulting in cost and energy savings. Based on an evaluation of pavements containing 30 percent RAP through the Long-Term Pavement Performance (LTPP) program, it has been determined that the performance of pavements containing up to 30 percent RAP is similar to that of pavements constructed from virgin materials with no RAP. This report is of interest to engineers, contractors, and others involved in the specification and design of asphalt mixtures for flexible pavements, as well as those involved in promoting the optimal use of RAP.

Peter Stephanos

Jorge E. Pagán-Ortiz

Director, Office of Pavement Technology

Director, Office of Infrastructure Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

With increased demand and limited aggregate and binder supply, hot mix asphalt (HMA) producers discovered that reclaimed asphalt pavement (RAP) is a valuable component in HMA. As a result, there has been renewed interest in increasing the amount of RAP used in HMA. While a number of factors drive the use of RAP in asphalt pavements, the two primary factors are economic savings and environmental benefits. RAP is a useful alternative to virgin materials because it reduces the use of virgin aggregate and the amount of virgin asphalt binder required in the production of HMA. Using RAP greatly reduces the amount of construction debris going into landfills, and it does not deplete nonrenewable natural resources such as virgin aggregate and asphalt binder. Ultimately, recycling asphalt creates a cycle of reuse that optimizes the use of natural resources and sustains the asphalt pavement industry.

More widespread use of higher amounts of RAP in asphalt mixtures requires support from State transportation departments and the HMA industry. State transportation departments have expressed concern over the lack of guidance on the use of high percentages of RAP (high RAP) mixtures, as well as the lack of information on their performance. As a result, there is a need for national guidance on best practices when using RAP and documented information about long-term performance of high RAP pavements.

The intent of this report is to provide state-of-the-practice information on including higher amounts of RAP in asphalt mixtures. The state of the practice for RAP use across the United States, as well as common challenges for increasing the use of RAP, are identified. Best practices applicable for the use of RAP are presented to identify general parameters that must be considered when developing specifications and to provide information on available resources and best practices for sourcing, processing, stockpiling, testing, designing, evaluating, producing, and placing high RAP mixtures, as well as practices to attain the best performance for high RAP mixtures.